PORTLAND, Maine — A 300-mile power cable would be buried on land in Maine and then run across the Atlantic Ocean floor to greater Boston under a proposal to tap Canada’s plentiful hydropower to meet the needs of power-hungry southern New England.

The so-called Green Line is one of several proposals across Vermont, Maine and New Hampshire aimed at fulfilling a goal by New England governors to tap up to 3,600 megawatts of renewable energy, lower electricity costs and offset losses as aging power plants go offline. It is expected to cost more than $1 billion.

“Our projects are in response to a really unusual moment in time, the six governors of New England coming together and indicating that they want to support bringing additional electrical infrastructure into New England for the sake of bringing clean energy into New England,” Ed Krapels of Anbaric, one of the Green Line partners, told The Associated Press.

After a bitter winter that saw big spikes in natural gas prices, the six states have come together to ensure a more reliable — and greener — power supply that can help stabilize prices in the region.

“It’s pretty huge,” said Chris Recchia, the commissioner of the Vermont Department of Public Service, about the states working so closely together. “To my knowledge it hasn’t been done before.”

In the next few months, the governors are expected to issue requests for proposals for 1,200 to 3,600 megawatts of transmission capacity that could carry wind and hydroelectric power from the northern reaches and Canada. They are working to ensure the region has a reliable supply of natural gas to avoid repeats of this winter’s extreme price spikes.

Many of the proposals have been talked about in utility circles for some time but came into sharper focus after January’s spike in natural gas prices. Those hikes significantly increased power costs for New England electric ratepayers, highlighting the need for alternative power sources such as hydro and wind, as well as reliable sources of natural gas.

“The level of urgency has probably increased as a result of the events in January,” said Tom Dunn, the president of VELCO, which manages the transmission grid in Vermont, a potential path to southern New England for Canadian hydropower. “I think the concern is that this stuff takes a long time to permit and build. This situation is going to be with us for a number of years.”

Patrick Woodcock, the governor’s energy chief in Maine, said something has to change because the region’s energy rates are sky high and there are consequences of relying too heavily on fossil fuels.

“There are a lot of costs to inaction,” he said.

Massachusetts and Connecticut are driving the push to bring clean hydropower from Canada to help the states meet their clean-energy goals. But the other four states — Vermont, New Hampshire, Rhode Island and Maine — agreed through the New England States Committee on Electricity, made up of state utility officials from the six states. They have agreed to share the costs because they would benefit from the overall reduction in energy costs, although the details of how that would be done remain to be worked out.

The Green Line is one of two such proposals in Maine, with a construction team including Maine-based Cianbro, as well as Anbaric Holding LLC of Massachusetts and Powerbridge of Connecticut. Their proposal is unusual in that it envisions a construction hybrid of burying cable underground — possibly along railroad tracks — in Maine and then running cable under the ocean to greater Boston — a total distance of about 300 miles.

Emera, based in Halifax, Nova Scotia, is leading a similar proposal to bring up to 1,100 megawatts of energy across Maine, in a project dubbed the Northeast Energy Link. Other proposals include the Northern Pass through New Hampshire; a proposal to run cables under Vermont’s Lake Champlain; and a smaller Anbaric proposal to bring New York power into the New England power grid in northwestern Vermont, also under a portion of Lake Champlain.

Anbaric, experienced in laying underwater power lines between New Jersey and New York, says the use of submarine cables is the most efficient method of transporting energy in terms of siting and permits. The Green Line proposal is set up to tap both wind energy from northern Maine and hydropower from Quebec, New Brunswick and Labrador.